Interbreed Matings in Dairy Cattle. IV. Growth Rate of Two-Breed Crosses

Abstract Body weights for all single crosses among Ayrshires, Brown Swiss, and Holsteins were compared to those of contemporary purebreds in six periods: birth to 6 months, 7 to 12, 13 to 16, 17 to 21, 22 to 24 months, and in first lactation. Least-squares techniques were used to estimate the effects of year-parity, season, breed groups, age, and the two-factor interactions with the linear and quadratic age effects. Year-parity had a significant influence on weights up to 12 months but not thereafter. Differences among purebreds were important at all ages. General combining abilities differed (P